Murdoch says 'clock' now on Fox-Sky deal

Rupert Murdoch and sons, Lachlan and James, are pushing for a Fox takeover of UK's Sky

Britain should judge Rupert Murdoch's bid for broadcaster Sky on the facts, not politics or it risks stifling inward investment after Brexit, James Murdochs says.

Appearing before an audience of media executives on Thursday, hours after the government referred Twenty-First Century Fox's $US15 billion ($A19 billion) bid for a detailed investigation, James Murdoch struck a combative tone in defence of his family's record in building a business that spans TV, film and news.

He was confident the country's independent regulators would assess the deal on its merits and not be swayed by politicians with scores to settle over how his father's newspapers had treated them over the decades.

"We have a clock on this now. We are confident it goes through," said Murdoch, who is chief executive of Twenty-First Century Fox and chairman of Sky.

The Murdochs returned to buy full control of Sky in December 2016, more than five years after a phone-hacking scandal at their now-defunct News of the World tabloid sank a previous attempt.

Since that failure, they have split their company in two, separating the newspapers from the entertainment assets to help to smooth the passage of the deal.

But their reputation remains damaged in Britain after a public inquiry revealed the close ties between Rupert Murdoch and prime ministers Margaret Thatcher, Tony Blair and David Cameron, creating the impression of puppet-master Murdoch pulling the strings of the country's politicians.

In response, Theresa May's government has been much more cautious, referring the bid for lengthy investigations and in one instance ignoring the advice of the media regulator Ofcom which had cleared it on grounds of broadcasting standards.

Earlier on Thursday Media Secretary Karen Bradley said Fox would now need to prove it could uphold broadcasting standards during a six-month review in order to secure the deal, following a series of sexual harassment and discrimination lawsuits at the Murdoch's Fox News network in the United States.

Asked if the Murdochs could be trusted after presiding over scandals at their British newspapers and later at Fox News, James Murdoch said the company had dealt effectively with the problems.

He added that the issue of inward investment would become even more important as the country prepares to leave the European Union.

"If the UK truly is open for business post-Brexit we'll look forward to moving through the regulatory review process and this transformative transaction for the UK creative sector becoming an affirmation of that claim," he said.

The government has given the Competition and Markets Authority 24 weeks to review the takeover on the impact it will have on broadcasting standards and media plurality.